It has been found that the surface of a blade which is in contact with a guide washer mounted around the cylindrical shank of the blade, between this surface of the blade and the turbomachine casing, could quite rapidly develop a relatively significant amount of wear when this guide washer has an annular boss on its face in contact with the aforementioned surface or “mounting plate” of the blade.
This annular boss is actually liable to wear away the surface of the mounting plate of the blade and form an annular groove therein, after which the entire surface of the guide washer will rub against the mounting plate of the blade and degrade it through wear.
This results in a risk of contact between the trailing edge of the blade and the turbomachine casing, which entails removing and replacing the variable-pitch blade. Such an operation is lengthy and expensive.
When the variable-pitch blade is made of austenitic steel and the guide washer is made of martensitic steel, this phenomenon of wearing of the blade mounting plate may occur rapidly and present a major problem.